This invention relates to optical encoders of the type having a rotary code disc, or some other movable code member, having a plurality of optical code tracks for modulating light in accordance with the position or movement of the code member. Such an optical encoder includes an optical system for illuminating the code tracks on the movable code member, and for directing the modulated light from the code tracks to a photodetector having a plurality of channels for converting the modulated light into corresponding electrical signals.